Electric Energy T&D - Index

Electric Energy T&D - EE Magazine March / April 2009 - Index

Designing and Populating Geospatial Systems to Support Advanced Applications for Field Automation
Typical conditions to address for GIS to Support field automation
The following are a number of typical situations that may need to
be addressed:
• customer to transformer/device connectivity – Customer
connectivity to a distribution transformer (in most cases),
or alternately to a primary metering device. Typically this
information is managed in a CIS or Meter Data Management
System, but if not, or if the quality of the data is questionable,
then this relationship needs to be established and business
processes need to be implemented to ensure that the
relationship is created correctly for new customers, and updated
when connections in the field are modified. This relationship
can be established in various ways, depending on the individual
case. Options include:
· Geocoding service addresses (computing a map
coordinate from street addresses using an street center
line network) and performing a spatial proximity search
to associate customers with transformers based on
distance, type, voltage, phasing, and class of service.
· If available, analyzing or tracing secondary and service
conductors between transformer and the customer
premises
· Field inventory
· If the utility is planning to install an advanced
metering infrastructure, then all meter locations
can be GPS-located when the meter upgrades are
performed and the serving transformer identified.
• Underground systems not complete – Very often underground
systems within manhole/vault/duct systems are either not
modeled or not populated correctly due to the complexity and
detail of the existing records. This class of data needs to be
researched either from existing detail drawings (manual or
CAD), physical field inspection, or a combination of the two.
• pad-mounted Switch Gear at High Level Only – If complex
devices are only modeled as the structure itself, showing
terminating conductors only, then additional detail on the
internal configuration will need to be captured. This requires
the correct representation in the GIS model depicting bus
connections, individual switches, fuses and elbows by phase.
This representation may be able to be determined from
examination of operating maps or schematics, by physical field
inspection, or a combination of the two.
• No phasing information – For many utilities whose initial
emphasis was on automated mapping, phasing information
is represented only by annotation, and then, often only on
selected device classes with users interpreting the symbology
and annotation to infer phasing information when needed.
By contrast, modern GIS models require this data explicitly
on all electrically connected features. If this data is available
for certain subsets of features, it may be possible to develop
software to propagate this to connected features, being careful
to enforce certain connectivity rules (i.e., a single phase feature
cannot feed a multiphase feature). Typically, operating maps
or schematics will contain sufficient information to be able to
infer phasing, but ambiguous situations may still require field
inspection.
6 I March-April 2009 Issue
The analysis of the existing GIS and related datasets needs to determine
the usability of the data. For each feature (entity) and attribute the
following types of characteristics must be understood:
• How many of the records have null data values?
• How many have illegal or non-plausible values?
• If there are interdependencies between fields or special business
rules, are these valid?
• Is there valuable information in comments fields or other
unstructured formats?
• Is the unstructured data in a form that can potentially be parsed
with software?
• Do records in other datasets contain identifiers that can be used to
correlate with the GIS?
• What is the correlation rate across records in different datasets?
This analysis should yield a type of “health and wealth” assessment
of the utility’s GIS and related databases. This will provide the kind
of information necessary to plan how the existing databases can
be processed to provide the required data structure and content to
support field automation.
The sidebar, Typical Conditions to Address for GIS to Support Field
Automation, highlights typical situations that may need to be addressed
based on the outcome of the current state assessment. Depending
on the overall assessment of data completeness and quality, a field
inventory may be required for the system as a whole, or hopefully
for only a subset of the network (i.e. overhead only, or underground
manhole/duct).
Action Plan
The current state assessment is followed by the development of an
action plan for the work needed to achieve the data organization,
content and quality required to support the field automation devices
and applications.
While the end state in terms of a GIS database design will be fairly
uniform across the industry, the important issue here is that each
individual organization will have a unique set of pre-existing conditions
to deal with. Therefore, the specific steps and activities that need to
be taken will be unique for each company. For each class of data being
addressed, some combination of the following activities will need to
occur:
• Combining two (or more) record sets into one, removing redundancy,
and resolving ambiguities
• Developing software to parse or decode unstructured data elements
into a structured format (i.e. address or comments fields)
• Setting up software and processes for human beings to analyze
exceptions and efficiently enter correct data into the database
• Locating and analyzing legacy manual maps, drawings, or records
to extract additional information needed to supplement automated
data